1. Field of Inventions
The present inventions relate generally to devices for delivering and installing surgical clips.
2. Description of the Related Art
There are many instances where surgical clips are secured to tissue within a patient. One example of such a procedure is the treatment of atrial fibrillation. Atrial fibrillation occurs when anatomical obstacles in the heart disrupt the normally uniform propagation of electrical impulses in the atria. These anatomical obstacles (called “conduction blocks”) can cause the electrical impulse to degenerate into several circular wavelets that circulate about the obstacles. The wavelets (called “reentry circuits”) disrupt the normally uniform activation of the left and right atria. Because of a loss of atrioventricular synchrony, the people who suffer from atrial fibrillation also suffer the consequences of impaired hemodynamics and loss of cardiac efficiency. They are also at much greater risk of strokes and other thromboembolic complications because of loss of effective contraction and atrial stasis. With respect to strokes, thrombus can form in left atrial appendage, break off, and cause a stroke. The risk of stroke for people with atrial fibrillation is about five (5) times that of those who do not have atrial fibrillation.
Electrosurgical devices have been used in minimally invasive procedures to form a set of three transmural epicardial encircling lesions that cures paroxysmal atrial fibrillation in most patients. The epicardial lesion set that typically cures paroxysmal atrial fibrillation includes an encircling lesion around the right pulmonary vein pair, an encircling lesion around the left pulmonary vein pair and an encircling lesion around the left atrial appendage. Additional epicardial lesions are frequently required for patients with persistent or permanent atrial fibrillation. A transmural “connecting” lesion that connects the lesion around the right pulmonary vein pair to the lesion around the left pulmonary vein pair may be required if these lesions do not overlap, and a transmural connecting lesion that connects the lesion around the left pulmonary vein pair to the lesion around the left atrial appendage may be required if these lesions do not overlap. Electrosurgical clamps may be used to form the epicardial encircling lesions and electrosurgical probes may be used to form the epicardial connecting lesions. Exemplary electrosurgical clamps and surgical probes are disclosed in U.S. Pat. Nos. 6,142,994 6,610,055 and U.S. Patent Pub. Nos. 2003/0158547 A1 and 2005/0119654 A1. In minimally invasive procedures, access to the heart is typically obtained via a thoracotomy and a relatively small (e.g. about 10 mm in diameter) access port.
There is, unfortunately, some likelihood that a patient's atrial fibrillation will not be cured by the above-described minimally invasive epicardial procedure and such a patient will also continue suffer from the associated increase in the risk of stroke. In context of more invasive atrial fibrillation treatments, such as open heart surgical maze procedures, one method of reducing subsequent stroke risk in patients is to isolate the interior of the atrial appendage from the left atria. This eliminates the possibility of thrombus within the atrial appendage entering the blood stream. The isolation may be accomplished by suturing the base of the atrial appendage closed, or by applying a clip by hand to epicardial surface at the base of the atrial appendage.
The present inventor has determined that although the use of a clip is a convenient way to isolate an atrial appendage, a need exist for a device that is capable of delivering a clip to a target tissue structure during minimally invasive surgical procedures, where application by hand is not possible.